The present invention relates to a plasma treatment apparatus, and more particularly to a plasma treatment apparatus such as a plasma etching apparatus or a plasma CVD apparatus utilizing plasma.
In manufacture of a semiconductor device, there has been often used a dry process in which plasma is utilized in an etching process or a CVD process.
There has been widely known a reactive ion etching by which an etchant gas is led into a vacuum chamber to form a plasma gas and a semiconductor wafer is etched by using generated ions.
An internal surface of the vacuum chamber in such a plasma treatment apparatus is usually coated with and protected by a plasma protection member. As such a plasma protection member, alumina has been conventionally used. When plasma is generated in the vacuum chamber, however, a part of a product such as ions collides with the internal surface of the vacuum chamber, which separates aluminum from alumina to be discharged in the chamber.
That is, when the aluminum is mixed in the plasma, the obtained mixture is led into the wafer as a contaminant.
Further, since the alumina discharges an oxygen gas as well as the aluminum, the oxygen gas mixed in the plasma adversely affects a photoresist or a shape to be formed when etching the wafer.
In order to solve such a problem, there has been proposed use of a protection member made of silicon carbide having a double structure in which a silicon carbide film is deposited on a sintered silicon carbide in place of using alumina as the plasma protection member.
An example of use of the silicon carbide for the plasma protection member is disclosed in Japanese patent laid-open publication No. Hei 10-139547.
However, there occur various problems even if the silicon carbide having such a double structure is used as the plasma protection member on the internal surface of the vacuum chamber.
One problem lies in that a high-frequency induced current for generating the plasma produces an eddy current in the silicon carbide and this eddy current breaks an electromagnetic field, which can cause a defect in a plasma density distribution or heat generation of the internal surface.
In order to eliminate the above-described problems, it is an object of the present invention to provide a plasma treatment apparatus capable of stably maintaining the state of the plasma in a chamber without discharging a contaminant from a chamber internal surface into the chamber.
The present invention provides a plasma treatment apparatus comprising a plasma reaction chamber having an internal surface covered with a plasma protection member, wherein the protection member is constituted by a sintered silicon carbide to which boron is added to enhance the resistivity and a silicon carbide film, which is deposited on the sintered silicon carbide and has high purity and low resistivity, includes filament grooves which partition the silicon carbide film.
Further, in the plasma treatment apparatus, it is desirable that a width of the filament groove is smaller than twice the thickness of an ion sheath of the plasma which can be generated in the plasma reaction chamber. Furthermore, it is desirable that a thickness of the silicon carbide film is in a range of 0.5 mm to 6 mm. Moreover, adjustment of the boron content of the sintered silicon carbide is desirable in order that the resistivity of the sintered silicon carbide is increased from 102-3 xcexa9xc2x7cm to 107-9 xcexa9xc2x7cm. It is to be noted that the protection member may be used for an inductively coupled plasma (ICP) window.